Abstract: The radar includes a linearly frequency-modulated microwave frequency signal generator (1), a transmitter-receiver antenna (2) and coupling means (3, 6; 48) in order to sample a local oscillation signal and an echo signal and in order to transmit these two signals to the inputs of a mixer (5) which provides at its output a subtractive beat signal between these two signals. The line lengths are adjusted in order to produce a static adjustment of the phase between the local oscillation signal and the interference antenna reflection signal. A phase control loop including an amplifier (36) and a low-pass filter (37) is connected between the output of the mixer and an input of a phase-shifting circuit (35; 54) placed in the local oscillation channel; the closed control loop cut-off frequency is just below the frequency of the subtractive beat signal.